This invention relates to a load handling vehicle, hereafter referred to as being of a kind specified, comprising a structure having a load carrying means at a front end of the vehicle, power means to raise the load carrying means, ground engageable propulsion means comprising a pair of front ground engageable wheels disposed one at each side of the vehicle and a pair of rear ground engageable wheels disposed one at each side of the vehicle, an operators seat, and a motor to provide power for said propulsion means to drive at least one of said pairs of wheels and for said power means to raise the load carrying means.
The invention is particularly concerned with a vehicle of the kind specified which is suitable for industrial load handling typically in warehouses or other situations where the vehicle is likely to experience restricted manoeuvring space. Hitherto such a material handling vehicle had a load carrying means which has conventionally comprised an upstanding mast mounted at the front of the vehicle and in front of the driver and a material handling implement which is displaceable up and down the mast. This mast is conventionally extendible to a considerable height over which the material handling implement can be displaced and may also comprise two or more sections which can be raised to increase its overall height and therefore the permissible lift height of the handling material implement.
The material handling implement may comprise a fork having, for example, a pair of tines, or a platform. For convenience both such vehicles will be referred to hereinafter as a lift truck.
In such known lift trucks the forward visibility of the driver when seated in the driver""s seat is through the mast structure so that the visibility is necessarily impaired. Also there is the disadvantage that the mast structure even in a collapsed condition stands at a considerable height which can cause loss of access of the vehicle through the doorways and warehouses and the like. A further disadvantage is that multiple and complex lifting mast sections of varying lengths for each lift height may be required for very high lift capabilities with consequential high manufacturing costs. Industrial lift trucks particularly those which are of relatively narrow width, for example less than 1.7 meters, are generally regarded as relatively unsophisticated vehicles and it is therefore necessary that the manufacturing costs of such a vehicle are minimised whilst ensuring that the lift truck is reliable and efficient and will, in use, comply with specified safety standards. This latter requirement being especially true of the stability of the lift truck during load handling.
GB-A-2264689 discloses an attempt to provide a solution to the above mentioned problem but suffers from the disadvantage that it is too large for operating inside a congested warehouse or industrial buildings, where such machines are, typically, intended to be used.
An object of the invention is therefore to provide a material handling vehicle whereby the above mentioned disadvantages are overcome or are reduced.
According to one aspect of the present invention we provide a material handling vehicle of the kind specified in which the load carrying means comprises a telescopic boom pivotally mounted to the structure at a rear end region of the boom for up and down swinging movement by said power means in a plane extending forwardly and rearwardly of the vehicle and the boom having a load carrying implement at a forward end region thereof, the front ground engageable wheels being driven by said motor and the rear ground engageable wheels being steerable and the seat having a region disposed generally underneath the seat in which the motor is disposed.
The rear ground engageable wheels may be undriven by said motor.
The axis of rotation of the crankshaft of the engine may be offset away from the centre line of the vehicle in a direction which is away from the boom.
The crankshaft may be offset away from the centre line of the vehicle in a direction which is away from the boom, for example, by up to about 100 mm.
This allows the space below the boom to be unobstructed by the engine. Thus, if desired, when lowered, the boom or a component connected to the boom and depending downwardly therefrom may be at least partly alongside the engine.
The boom may be offset, width-wise of the vehicle, substantially to overlie the front and rear wheels at one side of the vehicle and to provide clearance width wise of the truck for the driver""s seat to be disposed alongside the boom.
The vehicle preferably has an overall width of less than 1.2 meters.
The operator""s seat may be positioned within an operator""s compartment.
The ratio of the width of the operator""s compartment to the overall width of the vehicle may lie in the range 1:0.5 to 1:0.8.
The engine may be drivingly connected to the front wheels by hydrostatic drive means.
The load carrying implement may be offset widthwise of the vehicle from the boom so that the load carrying implement is disposed in a region which is disposed substantially centrally of the vehicle in a widthwise direction.
The operator""s compartment, including the seat, may be pivotally mounted relative to the structure about an axis entering width wise of the vehicle at a position disposed at the front of the compartment so that the compartment and seat may be pivoted upwardly and forwardly to provide access to the engine.
The axis of pivot of the boom may be disposed at a position which is less than 30% of the rear wheel diameter behind the axis of rotation of the rear wheel.
The overall boom length is 95% of the total machine length.
Accordingly, the present invention aims at achieving the stated object by providing a smaller, more compact, machine which may be less that 1.2 meters wide, 2.6 meters long and 2.17 meters high. This is achieved by disposing the engine under the cab and by offsetting the axis of rotation of the crankshaft of the engine away from the centre line of the machine in a direction which is away from the boom, for example by about up to about 100 mm thus, when lowered, allowing the boom or a component connected to the boom, and depending downwardly therefrom to be at least partly alongside the engine. Such a vehicle is relatively narrow and is capable of relatively inexpensive manufacture in combination with efficient load handling and lifting to a relatively great height whilst ensuring that the forward visibility of the truck driver is not unnecessarily impaired by components of the vehicle together with posessing stable load handling characteristics.